Buffer



Sept. 2, 1947. A. ANDERSON BUFFER Filed Aug. 26, 1943 2 Sheets-Sheet; l

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Sepfi; Z, 1347. L. A. ANDERSON BUFFER Filed Aug. 26, 1943 2 Sheets-Sheet 2 NM IT on &

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Patented Sept. 2, 1947 g i Lil .TES AT-ENT ()FF BUFFER Louis A. Anderson, Dayton, Ohio, assignor to General. Motors Corporation, Dayton, Ohio, a corporation of Delaware Application August 26, 1943; SerialNo; 500,162

2 Claims. (01. 267-1) UNITED S 1- 2 This invention relates to a butter and more 1y movable. along with the barrel 12. upon recoil. particularly to a barrel buffer for use on a 50 ca1i- The barrel extension I4 is provided with a prober Browning machine gun. jection i=5 which interlocks with the buffer mech At present, the 50 caliber Browning machine anism generally designated. by the reference nugun; is provided with a barrel buffer wherein. the 5 meral. 2G} The barrel buffer 20' is supported by bufiing action is produced by a plunger moving the stationary element 22', the construction of through: a. body of oil. In: such anarrangement, which is the same as now used with the oil .bufier the temperature materially affects-the rate of: fire on astandard gun. The outer shape and size of of the gun and it frequentl happensthatsome the barrel buffer 211 is similar to the shape and or all of the oilleaks out with the result that size of th present 011' type buffer and is comthe buffer i's-none too dependable. pl'etel y interchangeable therewith without modi- A large number of bufier' designs have been. fyi'ng any of the other gun parts. proposed inan efiort to eliminate the need. for Reference numeral 24 designates a conventionthe-use of oilinthe buffer, but these have proven a1 bolt buffer carried by the end plate It in acunsatisfactory for various reasons; some have: 1- cordance with standard practice. The bolt bufier increased the load on the back plate too much may be of the fiber disc type now used or it may or have decreased the rate of fire. Others have be of any other construction suitable for stopinterfered with the hand cocking of the gun or ping the movement of the bolt. have been impractical for other reasons. It is Referring nowto Fig. 2'in which there is shown an object of this invention to provide apractical a sectional view of my improved bufier' construcbuifer'which does not have any of the above-mention, reference numeral 30' designates the main tioned: disadvantages. bufier' cylinder which is made of steel and within Thus one object of this. invention. is to: provide whicha plurality of cast iron brake shoes- 32' area buffer which is operable at all temperatures adapted to reciprocate. A plunger 34 provided and elevations normally encountered. with a notch 36 at its forward end is adapted to Another object is to provide animproved' barinterlock with the barrel extension element [5 as rel. bufier which is completely interchangeable shown in Fig. 1. Upon recoil of the gun barrel with the present oil buffers now hr use on: 50 the plunger 34 is moved to the rear. A cam elecaliber machin guns. ment or wedge means 38 provided with a cam Further objects and? advantages of the. present surface inclined 10 with respect to the plunger invention will be apparent from the following 34' is slidably mountedon the plunger 34' as description, reference being had to' the acconrshown. Upon recoil of the barrel, movement of panying drawings, wherein a preferred form: of the plunger" 3 causesthe cam element 38 tocam the present invention is clearly shown. the brake shoes 32 into braking engagement wi-th In. the drawings: the inner wall of the cylinder 30. A spring 40 Fig. 1 is a fragmentary elevational view with surrounding the shank of the plunger 34 has itspartsbroken away showing somewhat diagram one end in engagement with the cam 38 and has matically' a standard machine gun provided with its other end arranged in engagement with the my improved, barrel. buffer; element 42' which abuts against the enlarged: Fig. 2 is alongitudinalsectional view through 40 portion 44 of the plunger 34. When the plunger my improved barrel bufier; 34' is first moved. to the. rear, the cam 38 pushes Fig. 3 is a view similar to Fi 2 showing the th shoes. 32" outwardly. The outward. pressure position ofthe parts when the barrel extension of the shoes is determined by the amount the has movedto its rearmostposition; spring 48 is compressed. The maximum pressure Fig. 4 is a cross sectional viewtaken on line 45 is. exerted? by the spring 4!! when the ends 46 of 4-4 of. Fig. 3; and the shoes are struck by the element 42.. When Fig. 5 is a fragmentary sectional view of. a the forward ends 46 become engaged by the elebu-fier showing a slightly modified type of brake ment 42, the shoes are forced to move inunison shoe. with the plunger 34 without. any further increase Referring now to Fig. 1 of the drawings, ref- 50 in pressure. erenc numeral ID designates generally the By virtue at this construction the spring. 4 8* breech. housing of a standard 50 caliber Browning. alone opposes the recoil of the barrel and barrel machine gun. Reference numeral l2 designates. extension at the beginning of the recoil movethe. barrelof the gunand reference numeral l4 merit and thenwhen the plunger 3 has moved designates the barrel extension whichis normalfar enough so that the brake shoes have been cammed outwardly, thebrake shoes afford increased resistance to the movement of the barrel and barrel extension. The arrangement is such that upon slow movement of the plunger 34, such as is produced upon hand cooking of the gun, the brake shoes 32 move to the rear Without being cammed outwardly. However, the inertia of the brake shoes is sufficient that upon very rapid movement of the plunger 34, the cam 38 first cams the shoes into braking engagement before the shoes have moved any appreciable distance to- Ward, the rear.

A coil spring 48 is arranged between the forward end wall 3| of the cylinder 30 and the guide washer 53. A pin 52 assists the spring 48 in holding the guide washer 50 in proper assembled relationship on the plunger 3%. Suitable lugs 5 are provided on the guide washer 53 so as to prevent rotation of the guide washer relative to the plunger. The washer 50 is provided with a side lug 5| which is adapted to engage in a slot (not shown) in the side wall of the element 22. The construction of the washer element 56 is the same as now used on the oil buffer and needs no further description. A flanged nut 53 is threaded onto the inner end 58 of the plunger 3 The nut 56 serves as an abutment for the cam element 38 and also has a flange which serves as an abutment for the brake shoes 32 as the plunger 34 moves forward. The nut 58 contacts the brake shoes 32 when the apparatus is at rest, as shown in Fig. 2, and when the plunger 3% is moving from its rear position to its forward position.

For purposes of illustration, I have shown five brake shoe segments, whereas it is obvious that the number of brake shoe segments may be varied. An uneven number of brake shoes is preferable so as to avoid having two opposed shoes assuming the full load. The clearance between the brake shoe segments is enough so that the plunger together with the brake shoes does not serve as a fluid tight piston assembly. The rear end of the cylinder 38 is closed by means of the element 33 which is threaded onto the cylinder 33 as shown. A clearance recess 3!] is provided in the element 33 so as to allow the plunger 34 to move to the rear of the cylinder 30.

In Fig. 5 I have shown a modified bufier arrangement in which the brake elements are provided with inserts ll! of brake lining material. In this modification, ball bearings 12 have been provided between the cam 38 and the brake shoes 32, The purpose of this ball bearing arrangement is to reduce the amount of friction between the cam 38 and the inclined surface of the shoe 32 so that the cam will have a better chance to cam the shoes into braking engagement before the shoes begin moving longitudinally Within the cylinder 33.

The ball bearings 12 roll within the race 24 which is long enough to allow the ball bearings to roll lengthwise therein during the camming action. The pin '56 returns the ball bearings to the front end of the race after each operation. Thus, as the plunger 3 moves forward, the nut 56 pushes the pin 16 inwardly so as to push the ball bearings to the front end of the slot. Upon recoil of the gun, the plunger 34 pushes the nut 56 away from the rear end of the brake shoes so that the ball bearings and the pin 16 are free to move as they please.

While I have shown the buffer used as a barrel buffer in a 50 caliber Browning machine gun, it is obvious that it could be used in other kinds of guns and in other apparatus where bulfer action is required.

A buffer of the type described hereinabove has the advantage that it does not vary in operation upon changes in temperature and elevation. Once the buffer leaves the factory it requires no further adjustment and is completely interchangeable with the existing oil buffers now in use. Furthermore, the buffer does not materially interfere with hand cocking of the gun since the brake shoes move along with the plunger out of contact with the cylinder wall when the plunger moves slowly.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. In a buffer, a hollow cylinder; said cylinder having an opening provided in the one end thereof; said one end having a projecting cylindrical portion of smaller outer diameter than the main cylinder and connected to the main cylinder by a flange which forms an external spring seat and an internal stop surface; piston means operable within said cylinder comprising a plurality of brake shoe segments having portions disposed within said hollow cylinder and having internal wedge surfaces; a plunger having a portion disposed substantially centrally within said cylinder and surrounded by said brake shoe segments, and wedge means slidably mounted on said plunger for wedging said brake shoe segments into braking engagement with the wall of said cylinder upon rapid movement of said plunger in one direction; a shoulder on said wedge means; a shoulder on said plunger; a spring surrounded by said brake shoe segments and engaging said shoulders for biasing said wedge means into engagement with said internal wedge surfaces; and a coil spring surrounding said plunger and said projecting cylinder portion and having one end in engagement with said plunger and having its other end in engagement with said spring seat for biasing said plunger outwardly of said hollow cylinder; said brake shoe segments having stop surfaces for engagement with said internal stop surface for limiting the movement of said segments and having portions extending outwardly of said cylinder and disposed between said first and second named springs so as to form a barrier between said springs.

2. In a buffer, a hollow cylinder; said cylinder having an opening provided in the one end thereof; said one end having a projecting cylindrical portion of smaller outer diameter than the main cylinder and connected to the main cylinder by a flange which forms an external springseat and an internal stop surface; piston means operable within said cylinder comprising a plurality of brake shoe segments having portions disposed within said hollow cylinder and having internal wedge surfaces; said brake shoe segments having stop surfaces for engagement with said internal stop surfaces for limiting the movement of said brake shoe segments in one direction; a plunger having a portion disposed substantially centrally within said cylinder and surrounded by said brake shoe segments, and wedge means slidably mounted on said plunger for wedging said brake shoe segments into braking engagement with the wall of said cylinder upon rapid movement of said p1unger in one direction; a shoulder on said wedge means; a shoulder on said plunger; a spring surrounded by said brake shoe segments and engaging said shoulders for biasing said wedge means into engagement with said internal wedge surfaces; and a coil spring surrounding said plunger and said projecting cylinder portion and having one end in engagement with said plunger and having its other end in engagement with said spring seat for biasing said plunger outwardly of said hollow cylinder; said coil spring having an outer diameter substantially equal to the outer diameter of said hollow cylinder.

LOUIS A. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

Number 15 Number France Apr. 11, 1939 

